Interlocking system for railroads



Sept. 10, 1935. A. LANGDON' INTERLOCKING S'YS'iEM FOR- RAILROAD-S Filed July 11, 1931 ENTO 4, M

Ji ATTORNEY- .ENW om Q. E 1 Huh .1 m 3 H. fi H w n w u q Jvll m u n L x W J N Patented Sept. 10, 1935 UNITED STATES PATENT OFFICE Andrew Langdon, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application July 11, 1931, Serial No. 550,130

13 Claims.

This invention relates in general to interlocking systems for railways and has more particular reference to a system of this character wherein a single device is protected against misuse by means of two time measuring devices measuring, respectively, different lengths of time, so as to give time locking of different durations.

In interlocking systems it may occur that a signal after being put to clear may then be changed to stop preparatory to moving a track switch or the like and obviously, if an approaching train is proceeding fast enough, or is near enough to the switch, at the time the signal is put to stop, the switch may be thrown under the train or the train proceeding at a fast rate may be forced to take a diverging route at too great a speed for safety, in all events making for a dangerous condition.

To prevent such a contingency, it is desirable to provide means requiring a given lapse of time after a signal is put to stop before the control of a track switch or the like is given to the operator.

With the above and other objects in view, it is proposed, in accordance with this invention, to provide timing means to measure different lengths of time during which control of a track switch, for example, is withheld from an operator subsequent to his placing a signal at stop, with the different times automatically made effective depending upon signal aspects.

Further objects, purposes and characteristic features of the present invention will appear as the description progresses, reference being made to the accompanying drawing showing, solely by way of example, and in no manner whatsoever in a limiting sense, two forms which the invention can assume.

In the drawing:

Fig. 1 is a wholly diagrammatic view showing one form of this invention.

Fig. 2 is a wholly diagrammatic fragmentary view showing a slightly modified form of the invention.

Referring now to the drawing, and first to Fig. 1, there is here shown a stretch of track I, divided into signalling blocks A, B, C by insulating joints 2, and having a diverging route D, controlled by a track switch TS. The blocks A, B and C are provided with usual track relays T T and T At the entrance to block B, east bound traffic being considered, is a distant signal S having a single blade which can assume clear, caution or stop positions, and, while shown as of the semaphore type, it can equally well be of any other usual or desired type of signal.

At the entrance to block C, from which block the diverging route D branches out, is positioned a home signal S having an upper signal blade 5 S A, and a lower signal blade 3, the upper blade controlling traffic over the main line and the lower blade controlling traffic over the diverging route or over the main route with track circuits occupied.

The signal S is controlled by a signal lever 5 L, which can be placed by an operator either in normal or reverse positions N and R respectively. These signals S and S are of the semiautomatic type, and are jointly controlled by 15 traffic in an automatic manner, and by the signal lever controlled by an operator.

A relay H is employed, which has an energizing circuit passing through the track switch contactor 3, which is closed when the track switch 20 is in normal position, and through a contact finger 4 and front point of track relay T of the lock section C, whereby it is apparent that when the signal lever 3 L is put at reverse, the upper blade S A is placed at proceed if relay H is en- 25 ergized, the signal control for the upper blade passing through contact finger 5 and front point of relay H. On the other hand, if relay H is down, due to the track switch being in reverse position, or due to occupancy of the track section C, the lower blade 8 B is put at its least restrictive position, which is caution. With the signal lever placed at normal, both of the arms of the signal S go to stop.

The distant signal S and the home signal S are interlocked in any usual manner, it being deemed unnecessary for the purpose of this invention to describe or show the interlocking, so that S moves to proceed when S A moves to proceed or caution, S goes to caution when S 13 moves to caution and S goes to caution when S A and S B go to stop. S of course automatically goes to stop upon occupancy of block B.

A lock relay L, is employed, which is arranged to lock up the track switch TS, when the relay is de-energized, so that the switch cannot be moved. It is thus necessary, in order for the operator to move the track switch, that the lock relay L first be energized.

Employed in this system are two time elements S ST and S LT which, respectively, measure a relatively short time and a relatively long time, after initiation, before they operate to close a Contact in the circuit in which they are placed. 55

These elements can be of any usual or desired type, but as shown in Fig. 1, are contemplated as being of the mechanical type and arranged to be initiated when signal lever S L is placed at normal, so that a predetermined time after the signal lever is placed at normal the time element closes a contact in its circuit. The time elements can be of a character, for example as shown in Adler, 1,638,793 August 9, 1927, and R. C. Leake 1,535,923 April 28, 1925.

The energizing circuits for the lock relay L are three in number, and include a portion common to the three, connected to three multiple branches and can be traced from one terminal of a source of energy, to relay L, wire 6, the short time element S ST, wire i, contact finger 8 and front point of relay T wire 9, and then through one of the three multiple paths to include wires l0 and H, contact finger I2 and front point of relay T wire I3, contact finger M and front point of relay T wires l5 and 16 to the other terminal of the source of energy to constitute an upper branch; a lower branch including wire ll, contact finger l8 and front point of a stick relay HS, wires i9, 20, and i6; and a middle branch including wires l9 and 22, the long time element S LT, and wires 23, 2E] and I6.

From the above traced circuits for the lock relay L it appears that energization of this look relay is always dependent upon the short-time element S ST, and is also dependent upon the long time element S LT, unless either both relays T and T are up, or in other words unless track sections A and B are unoccupied, or unless the lower shunt path is completed, which requires that relay HS be up.

Unless relay T is up, or in other words, unless the lock section C is unoccupied, contact finger 8 operates to open the energizing circuit so that the lock relay cannot in any event pick up and give control of the track switch to the operator.

The control of the relay HS is dependent upon the H relay, and the signal lever 8 L, relay HS having an energizing circuit which includes the lower arm of signal lever S L, wires 24 and 25, contact finger 26 and back point of relay H, wires 21 and 28, and the relay HS, and when once picked up, relay HS sticks up through a stick circuit which is obvious from the drawing, this stick circuit being desirable for providing for follow-up movements over the track, the details of which need not be here discussed, since they are unnecessary for the proper understanding of the present invention.

With the system as above described, if the signal lever 8% be moved from normal N, to reverse R, the signal blade S A goes to proceed, and the signal blade S goes to proceed, provided the track switch is set normal, (N), as shown, and the section C is unoccupied, as shown. The route is now set up for through trafiic along the main track.

Let us assume now that an east bound train has accepted the signal S at proceed, and then the operator decides to move the signal blade S A to stop by moving the signal lever to normal. Under these conditions the approaching train, which has passed signal S at proceed, and hence is proceeding at a fast speed, will be faced by a stop signal on reaching, or first sighting, signal S and if the operator were permitted to move the track switch TS immediately after putting the signal to stop, either the train would run into the switch when it is opened, or might be derailed by taking the diverging route at too high a speed. In the interest of safety, under such conditions, it is necessary that SllffiClEIlt time be given for the approaching train to pass over the track switch, or at least to occupy the lock section C, before the operator is given control of the track switch and this time is considered properly covered by the time of the long time element S LT.

Thus, when the operator puts the signal lever 1 S L to normal, with the track switch TS at normal, relay H is up, and relay HS cannot pick up, whereby the lower shunt path around the long time element is open at contact finger i8 and the upper shunt path is open at either 44 or 52, due to l the approaching train, whereby the lock relay L cannot receive energy until after the long time element S LT has closed its circuit.

Assuming now that the track switch is set or the divergin route, and the signal arm 5 B at caution, the signal S will be at caution, and an approaching train, on passing this signal S will be warned that the next signal may be at stop and hence will be proceeding at a relatively low speed and prepared to stop at the next 2 signal. Under such conditions, if the operator move the signal lever from reverse to normal, the signal blade S B goes to stop, and the approaching train, if the signal S is visible within braking distance from the entrance of the block C, at 3 the slow speed at which the train is proceeding, can stop before reaching the track switch. If, however, the engineer is not alert, or if the signal S is positioned so that it becomes visible to the approaching train only after the train 3 has approached closer to the entrance to block C than the safe braking distance, then it is clear that sufficient time should be given the approaching train to occupy the section C, and lock up the track switch, before the operator is given control of the track switch. Otherwise the switch might be thrown under the approaching train.

Under the conditions assumed, on moving the signal lever S L to normal, the relay HS is picked up through its pick-up circuit, since contact 45 finger 26 is down, because the track switch, un-

der the assumed conditions, is set at reverse, thus to de-energize H. If relay HS is picked up, it

sticks up through its contact finger 29 and front point, and hence the lower shunt path, including 5 contact finger E8 of relay HS, is closed so as to shunt out the long time element. Accordingly, the lock relay L picks up after the short time interval has elapsed from the time the signal lever was put to normal, to thereby give control of the track switch to the operator. This short-time is chosen to be suificient to allow the oncoming train either to stop before reaching the switch, or to lock up the switch by occupying the section C. 6

If an approaching train has not reached the section A, the upper shunt path is intact and hence only the short-time interval is operative, as clearly, under these conditions, no danger exists.

While the invention has been described as used in connection with a signal and track switch, it obviously can be used in other connections, and clearly the initiation of the time elements, and the selection of the time elements, can be dependent on automatically controlled relays or the like such as used in centralized trafiic control systems or other systems, instead of being dependent upon the manual act of moving the signal control lever S L.

Referring now to Fig. 2, the modification herein shown includes time elements of a somewhat different type such for example, as shown in the application of O. S. Field, Ser. No. 442,022 filed April 5, 193:). These elements operate to close the circuits in which they are included, a predetermined time after they are initiated, and are initiated by the energization of windings 3t and 33, respectively, for the short and long time elements, said elements being identified in Fig. 2 as ST and LT.

The lock relay L is controlled in the same manner as in Fig. l, and controls the track switch in the same manner as described above.

In the form shown in Fig. 2, the lower signal lever, identified as S 14 can either be an additional signal lever, or it can be the lower signal lever of Fig. l, which, in controlling the relay HS, also controls the energizing circuit for the initiating elements 353 and 38 of the timing devices, this initiating circuit including lever S L wire 32, contact finger and back point of lock relay L wire 3 and then through multiple arms to the initiating elements 38 and 3E.

The control of the lock relay L is identical with that described in Fig. 1, it being dependent upon contact finger 3 of the track relay T and all the three multiple branches the upper of which includes contact fingers Hi and I2 of track relays T and T the lower of which includes contact finger I8 of relay HS, and the middle arm of which includes the long time element LT It should be clear from the above that a system has been provided by this invention whereby to safeguard in an automatic manner against accident, unnecessary delay being avoided in the operation of switches, signals and the like by providing sufiicient time to safeguard an oncoming train without using a surplus of time with resulting delay.

The above rather specific description of two forms of systems embodying the present invention, has been given solely by way of illustration, and is not intended, in any manner whatsoever, in a limiting sense. Obviously, this invention can assume many difierent physical forms, and is susceptible of numerous modifications, and all such forms and modifications, are intended to be included by this invention, as come within the scope of the appended claims.

Having described my invention, I now claim:-

1. In a railway interlocking system, in combination, a main line track having a turn out, a home signal, a track switch governing the turn out, manual control means for the signal, and means for withholding control of the switch for various predetermined times after the home signal has been put to stop.

2. In a control system, in combination, a main line track having a turn out, a home signal and a track switch governing the turn out, manual control means for the signal and switch, a distant signal, and means dependent upon whether or not an approaching train has accepted the distant signal, for withholding control of the switch for various predetermined times after the home signal has been put to stop.

3. In a railway interlocking system, in combination, a main line track having a turn out, a home signal and a track switch governing the turn out, manual control means for the signal and switch, a distant signal, and means dependent upon whether an approaching train has accepted the distant signal at clear, or at a restrictive indication, for withholding control of the switch for various predetermined times after the home signal has been put to stop.

4. In a control system, in combination, a main line track having a turn out, a home signal, a track switch governing the turn out, manual control means for the signal, a distant signal, and means for withholding control of the switch for various predetermined times after the main signal has been put to stop, a relatively long or a relatively short time being imposed, depending on whether an approaching train had, or had not, accepted the distant signal at the time the main signal was put to stop.

5. In a control system, in combination, a main line track having a turn out, a home signal, a track switch governing the turn out, manual control means for the signal, a distant signal, and means for withholding control of the switch for various predetermined times after the main signal has been put to stop, a long or a short time being imposed, depending on whether an appro-aching train had, or had not, accepted the distant signal at the time the main signal was put to stop and also according to whether or not an approaching train had accepted the approach signal at clear, or at a restrictive indication.

6. In an interlocking system for railways, a main line track and a turn out track, a governing home signal and track switch, a power-operated switch machine, a control circuit for the switch machine, means for closing the control circuit including a short time element and a manual lever for the home signal in normal position, a distant wayside signal, a long time element, an means inserting the long time element into the control circuit, depending on whether or not a train had accepted the distant signal at the time the home signal was manually put to stop.

7. In an interlocking system for railways, a main line track and a turn out track, a governing home signal and track switch, a power-operated switch machine, a control circuit for the switch machine, means for closing the control circuit including a short time element and a manual lever for the home signal in normal position, a distant wayside signal, a long time element, and means automatically inserting the long time element into the control circuit, depending on whether or not a train had accepted the distant signal at the time the main signal was manually put to stop, and also depending on whether the approaching train had accepted the distant signal at clear or at a restrictive indication.

8. In an interlocking system for railways, a main line track and a turn out track, a governing home signal and track switch, a power-operated switch machine, a control circuit for the switch machine, means for closing the control circuit for the switch machine including a short time element and a manual lever for the home signal in normal position, a distant wayside signal, a long time element, and means automatically inserting the long time element into the control circuit, depending on whether or not a train had accepted the distant signal at the time the home signal was manually put to stop, and also depending on whether the approaching train had accepted the distant signal at clear or at a restrictive indication, the long time element being inserted into the control circuit on condition that the distant signal had been accepted at clear, whereby to allow time for the train to pass the switch before control of the switch is given to the operator.

9. In combination, a section of railway track, a track switch in said section, a signal governing traffic over said track switch, a lock relay which if deenergized prevents power operation of said track switch, and means for preventing closure of an energizing circuit for said lock relay when said signal is at proceed and for a certain period of time following placing of said signal at stop with said track switch assuming the main track position and for increasing said period of time if there is a train approaching said signal.

10. In combination, a section of railway track, a track switch in said section, a signal governing traffic over said track switch, a lock relay which if deenergized prevents power operation of said track switch, and means for preventing closure of an energizing circuit for said lock relay when said signal is at proceed and for a certain period of time following placing of said signal at stop and for increasing said period of time if there is a train approaching said signal within a predetermined distance.

11. In combination, a section of railway track, a track switch in said section, a signal governing trafiic over said track switch, a lock relay which if deenergized prevents power operation of said track switch, and means for preventing closure of an energizing circuit for said lock relay when said signal is at proceed and for a certain period of time following placing of said signal at stop and for increasing said period of time if there is a train approaching said signal Within a predetermined distance unless said track switch assumes the take-siding position.

12. In combination, a detector track section containing a railway switch, a signal for governing the movement of traflic over the switch, manual control means for the signal, and means controlled in accordance with the condition of occupancy of said detector section for withholding control of the switch for various predetermined times after said manual control means is operated to put the signal to stop,

13. In combination with a railway switch, a signal governing traffic over said switch, a lever controlling said signal, means for preventing operation of said switch for a predetermined interval of time after said lever is operated to place said signal at stop, and apparatus responsive to traffic conditions adjacent said switch for at times prolonging said interval of time.

ANDREW LANGDON. 

